This invention relates to a semi-automatic hydraulic excavator.
In hydraulic excavators such as a loading shovel and a power shovel, a number of control levers such as a boom lever, an arm lever, a bucket lever and a rotation lever are provided. An operator manually operates these control levers to control the corresponding hydraulic control valve and thereby carries out work such as excavating and dumping soil. When a sequence of work, for example, excavating soil, dumping the excavated soil into a dump truck and then bringing the bucket back into the excavation posture for another excavation is to be carried out with a loading shovel, plural operations must be conducted simultaneously, i.e. a compound operation must be performed.
In a conventional hydraulic excavator, an operator is required to carry out such compound operation, and accordingly the operator must be highly skilled and even a highly skilled operator should put forth tremendous efforts which bring about deal of fatigue. It is also disadvantageous that in a large loading shovel in the prior art it is fairly difficult to watch the movement of the bucket from the operator's seat and the bucket is likely to be destroyed by mistakenly hitting against the front part of the track thereof.